Here’s my suggestions:
1. In theory, you can save money by building an AR. However, unless you buy a completed upper, you will need some fairly expensive tools. If you don’t have access to these tools, their cost will more than offset any savings from the kit.
Further, AR’s are a little involved in their workings. When building one, it helps to know how things are supposed to work. If you’re not already familiar with AR functioning, you’re better off getting a complete rifle for your first one and then maybe building your second one.
2. Make sure you’re getting a 5.56 (military) chamber, not a .223 (commercial) chamber. Mil-spec ammo doesn’t always work too well in a .223 chamber.
3. Be sure and get a chrome [b]lined[/b] bore. Note that the term “chrome-moly” isn’t the same - it refers to the barrel steel, not to whether or not the barrel is lined.
4. As mentioned above, get a flat top.
5. If you just want a slightly shorter stock, swap the existing stock out with a military surplus A-1 stock (or get a C-1 stock from Cavalry Arms).
6. Look at the mid length handguards as sold on Armalite and RRA rifles. I really like these. Note, though, that these are essentially non-standard and will limit some of the accessories you can use on them.
7. Buy [b]only[/b] USGI magazines!! The exception to this is if you need a reduced capacity for hunting purposes.
8. As mentioned above, avoid muzzlebrakes. They look cool, but you’ll get real tired of having the muzzle blast redirected back towards you.
9. Incidentally, just because the barrel is 16 inches long doesn’t necessarily make it light weight – there can be a lot of steel underneath the handguard!!
Just my opinions, of course. Welcome aboard.